stupidcreature It worked fine on that release, but people using third-party launchers couldn't see it on their homescreen after installing it. That's because the isolation was preventing third-party launchers from seeing it.
The latest release makes it so third-party launchers that you are using can see the thermometer app and display it on your homescreen.
If you hadn't changed a launcher, it's completely expected that you could see it just fine.